Various investigators have been studying hormonal therapy for breast and endometrial cancer as well as for the prevention and treatment of bone loss and for treatment of endometriosis. The main approaches for the treatment of already developed breast cancer are related to the inhibition of estrogen action and/or formation. The role of estrogens in promoting the growth of estrogen-sensitive breast cancer is well recognized (Lippman, Semin. Oncol. 10 (suppl. 4): 11-19, 1983; Sledge and McGuire, Cancer Res. 38: 61-75, 1984; Wittliff, Cancer 53: 630-643, 1984; Poulin and Labrie, Cancer Res. 46: 4933-4937, 1986).
Estrogens are also known to promote the proliferation of normal endometrium. Chronic exposure to estrogens unopposed by progesterone can lead to the development of endometrial hyperplasia which predisposes to endometrial carcinoma (Lucas, Obstet. Gynecol. Surv. 29: 507-528, 1974). The incidence of endometrial cancer increases after menopause, especially in women receiving estrogen therapy without simultaneous treatment with progestins (Smith et al., N. Engl. J. Med. 293: 1164-1167, 1975; Mack et al., N. Engl. J. Med. 294: 1262-1267, 1976).
Various investigators have been studying hormone-dependent breast and endometrial cancer. A known form of endocrine therapy in premenopausal women is castration most commonly performed by surgery or irradiation, two procedures giving irreversible castration. Recently, a reversible form of castration has been achieved by utilizing Luteinizing Hormone-Releasing Hormone Agonists (LHRH agonists) which, following inhibition of secretion of bioactive Luteinizing Hormone (LH) by the pituitary gland, decrease serum estrogens to castrated levels (Nicholson et al., Brit. J. Cancer 39: 268-273, 1979).
Several studies show that treatment of premenopausal breast cancer patients with LHRH agonists induces responses comparable to those achieved with other forms of castration (Klijn et al., J. Steroid Biochem. 20: 1381, 1984; Manni et al., Endocr. Rev. 7: 89-94, 1986). Beneficial effects of treatment with LHRH agonists have also been observed in postmenopausal women (Nicholson et al., J. Steroid Biochem. 23: 843-848, 1985).
U.S. Pat. No. 4,071,622 relates to the use of certain LHRH agonists against DMBA-induced mammary carcinoma in rats.
U.S. Pat. No. 4,775,660 relates to the treatment of female breast cancer by use of a combination therapy comprising administering an antiandrogen and an antiestrogen to a female after the hormone output of her ovaries has been blocked by chemical or surgical means.
U.S. Pat. No. 4,775,661 relates to the treatment of female breast cancer by use of a therapy comprising administering to a female, after the hormone output of her ovaries has been blocked by chemical or surgical means, an antiandrogen and optionally certain inhibitors of sex steroid biosynthesis.
U.S. Pat. No. 4,760,053 describes a treatment of selected sex steroid dependent cancers which includes various specified combinations of compounds selected from LHRH agonists, antiandrogens, antiestrogens and certain inhibitors of sex steroid biosynthesis.
In U.S. Pat. No. 4,472,382 relates to treatment of prostatic adenocarcinoma, benign prostatic hypertrophy and hormone-dependent mammary tumors with specified pharmaceuticals or combinations. Various LHRH agonists and antiandrogens are discussed.
WIPO International Publication WO921 05763 discuss certain 16,16 disubstituted androstene steroid compounds for hair growth and skin disorders. International Patent Application PCT/W086/01105, discloses a method of treating sex steroid dependent cancers in warm-blooded animals which comprises administering specific pharmaceuticals and combinations. Antiandrogens, antiestrogens, certain inhibitors of sex steroid biosynthesis and blocking of hormonal output are discussed.
The inventor's co-pending U.S. patent application No. 07/321926 filed Mar. 10, 1989, relates to a method of treatment of breast and endometrial cancer in susceptible warm-blooded animals which may include inhibition of ovarian hormonal secretion by surgical means (ovariectomy) or chemical means (use of an LHRH agonist, e.g. [D-Trp.sup.6, des-Gly-NH.sub.2.sup.10 ]LHRH ethylamide, or antagonists) as part of a combination therapy. Antiestrogens, androgens, progestins, inhibitors of sex steroid formation (especially of 17.beta.-hydroxysteroid dehydrogenase- or aromatase-catalyzed production of sex steroids), inhibitors of prolactin secretion and of growth hormone secretion and ACTH secretion are discussed.
Androgen receptors have been shown to be present in normal (Witlift, In: Bush, H. (Ed.), Methods in Cancer Res., Vol. 11, Acad. Press, New York, 1975, pp. 298-304; Allegra et al., Cancer Res. 39: 1447-1454, 1979) and neoplastic (Allegra et al., Cancer Res. 39: 1147-1454, 1979; Engelsman et al., Brit. J. Cancer 30: 177-181, 1975; Moss et al., J. Ster. Biochem. 6: 743-749, 1975; Miller et al., Eur. J. Cancer Clin. Oncol. 2: 539-542, 1985; Lippman et al., Cancer 38: 868-874, 1976; Allegra et al., Cancer Res. 39: 1447-1454, 1979; Miller et al., Eur. J. Clin. Oncol. 21: 539-542, 1985; Lea et al., Cancer Res. 49: 7162-7167, 1989) as well as in several established breast cancer cell lines (Lippman et al., Cancer Res. 36: 4610-4618, 1976; Horwitz et al., Cancer Res. 38: 2434-2439, 1978; Poulin et al., Breast Cancer Res. Treatm. 12: 213-225, 1988). Androgen receptors are also present in dimethylbenz(a)anthracene (DMBA)-induced mammary tumors in the rat (Asselin et al., Cancer Res. 40: 1612-1622, 1980).
Androgen receptors have also been described in human endometrium (MacLaughlin and Richardson, J. Steroid Biochem. 10: 371-377, 1979; Muechler and Kohler, Gynecol. Invest. 8: 104, 1988). The growth inhibitory effects of the androgen methyltrienolone (R1881), on endometrial carcinoma in vitro have been described (Centola, Cancer Res. 45: 6264-6267, 1985).
Recent reports have indicated that androgen receptors may add to the selective power of estrogen receptors or even supplant estrogen receptors as best predicting response to endocrine therapy (Teulings et al., Cancer Res. 40: 2557-2561, 1980; Bryan et al., Cancer 54: 2436-2440, 1984).
The first androgen successfully used in the treatment of advanced breast cancer is testosterone propionate (Nathanson, Rec. Prog. Horm. Res. 1: 261-291, 1947). Many studies subsequently confirmed the beneficial effect of androgens on breast cancer (Alan and Herrman, Ann. Surg. 123: 1023-1035; Adair, Surg. Gynecol. Obstet. 84: 719-722, 1947; Adair et al., JAMA 140: 1193-2000, 1949). These initial results stimulated cooperative studies on the effect of testosterone propionate and DES which were both found to be effective in producing objective remissions. (Subcommittee on Steroid and Cancer of the Committee on Research of the Council on Pharmacy and Chemistry of the Am. Med. Association followed by the Cooperative Breast Cancer Group under the Cancer Chemotherapy National Service Center of the NCI who found that testosterone propionate improved remission rate and duration, quality of life and survival (Cooperative Breast Cancer Group, JAMA 188, 1069-1072, 1964)).
A response rate of 48% (13 of 27 patients) was observed in postmenopausal women who received the long-acting androgen methonolone enanthate (Kennedy et al., Cancer 21: 197-201, 1967). The median duration of survival was four times longer in the responders as compared to the non-responder group (27 versus 7.5 months). A large number of studies have demonstrated that androgens induce remission in 20 to 40% of women with metastatic breast cancer (Kennedy, Hormone Therapy in Cancer. Geriatrics 25: 106-112, 1970; Goldenberg et al., JAMA 223: 1267-1268, 1973).
A response rate of 39% with an average duration of 11 months has recently been observed in a group of 33 postmenopausal women who previously failed or did not respond to Tamoxifen (Manni et al., Cancer 48: 2507-2509, 1981) upon treatment with Fluoxymesterone (Halostatin) (10 mg, b.i.d.). Of these women, 17 had also undergone hypophysectomy. There was no difference in the response rate to Fluoxymesterone in patients who had previously responded to Tamoxifen and in those who had failed. Of the 17 patients who had failed to both Tamoxifen and hypophysectomy, 7 responded to Fluoxymesterone for an average duration of 10 months. Among these, two had not responded to either Tamoxifen or hypophysectomy.
The combination Fluoxymesterone and Tamoxifen has been shown to be superior to Tamoxifen alone. In fact, complete responses (CR) were seen only in the combination arm while 32% showed partial response (PR) in the combination arm versus only 15% in the monotherapy arm. In addition, there were only 25% of non-responders in the combination therapy arm versus 50% in the patients who received TAM alone (Tormey et al., Ann. Int. Med. 98: 139-144, 1983). Moreover, the median time from onset of therapy to treatment failure was longer with Fluoxymesterone+Tamoxifen (180 days) compared to the Tamoxifen arm alone (64 days). There was a tendency for improved survival in the combination therapy arm (380 versus 330 days).
The independent beneficial effect of an androgen combined with an antiestrogen is suggested by the report that patients who did not respond to Tamoxifen could respond to Fluoxymesterone and vice versa. Moreover, patients treated with Tamoxifen and crossing over to Fluoxymesterone survived longer that those treated with the reverse regimen (Tormey et al., Ann. Int. Med. 98: 139-144, 1983).
Since testosterone propionate had beneficial effects in both pre- and post-menopausal women (Adair et al., J. Am. Med. Ass. 15: 1193-1200, 1949), it indicates that in addition to inhibiting gonadotropin secretion, the androgen exerts a direct inhibitory effect on cancer growth.
Recent in vitro studies describe the relative antiproliferative activities of an androgen on the growth of the estrogen-sensitive human mammary carcinoma cell line ZR-75-1 (Poulin et al. "Androgens inhibit basal and estrogen-induced cell proliferation in the ZR-75-1 human breast cancer cell line", Breast Cancer Res. Treatm. 12: 213-225, 1989). As mentioned above, Poulin et al. (Breast Cancer Res. Treatm. 12: 213-225, 1989) have found that the growth of ZR-75-1 human breast carcinoma cells is inhibited by androgens, the inhibitory effect of androgens being additive to that of an antiestrogen. The inhibitory effect of androgens on the growth of human breast carcinoma cells ZR-75-1 has also been observed in vivo in nude mice (Dauvois and Labrie, Cancer Res. 51: 3131-3151, 1991).
As a possible mechanism of androgen action in breast cancer, it has recently been shown that androgens strongly suppress estrogen (ER) and progesterone (PgR) receptor contents in ZR-75-1 human breast cancer cells as measured by radioligand binding and anti-ER monoclonal antibodies. Similar inhibitory effects were observed on the levels of ER mRNA measured by ribonuclease protection assay. The androgenic effect is measured at subnanomolar concentrations of the non-aromatizable androgen 5.alpha.-dihydrotestosterone, regardless of the presence of estrogens, and is competitively reversed by the antiandrogen hydroxyflutamide (Poulin et al., Endocrinology 125: 392-399, 1989). Such data on estrogen receptor expression provide an explanation for at least part of the antiestrogenic effects of androgens on breast cancer cell growth and moreover suggest that the specific inhibitory effects of androgen therapy could be additive to the standard treatment limited to blockade of estrogens by antiestrogens.
Dauvois et al. (Breast Cancer Res. Treatm. 14: 299-306, 1989) have shown that constant release of the androgen 50.alpha.-dihydrotestosterone (DHT) in ovariectomized rats bearing DMBA-induced mammary carcinoma caused a marked inhibition of tumor growth induced by 17.beta.-estradiol (E.sub.2). That DHT acts through interaction with the androgen receptor is supported by the finding that simultaneous treatment with the antiandrogen Flutamide completely prevented DHT action. Particularly illustrative of the potent inhibitory effect of the androgen DHT on tumor growth are the decrease by DHT of the number of progressing tumors from 69.2% to 29.2% in E.sub.2 -treated animals and the increase by the androgen of the number of complete responses (disappearance of palpable tumors) from 11.5% to 33.3% in the same groups of animals. The number of new tumors appearing during the 28-day observation period in estradiol treated animals decreased from 1.5.+-.0.3 to 0.7.+-.0.2 per rat during treatment with the androgen DHT, an effect which was also reversed by the antiandrogen Flutamide. Such data demonstrate, for the first time, that androgens are potent inhibitors of DMBA-induced mammary carcinoma growth by an action independent from inhibition of gonadotropin secretion and suggest an action exerted directly at the tumor level, thus further supporting the in vitro data obtained with human ZR-75-1 breast cancer cells (Poulin et al., Breast Cancer Res. Treatm. 12: 213-225, 1988).
The natural androgens testosterone (TESTO) and dihydrotestosterone (DHT) are formed from conversion of androstenedione into TESTO by 17.beta.-hydroxysteroid dehydrogenase and then TESTO into DHT by the action of the enzyme 5.alpha.-reductase. The adrenal precursor 5-androst-5-ene-3.beta.,17.beta.-diol can also be converted into TESTO by action of the enzyme 3.beta.-hydroxysteroid dehydrogenase/.DELTA..sup.5 .DELTA..sup.4 isomerase (3.beta.-HSD).
Since the natural androgens TESTO and DHT have strong masculinizing effects, numerous derivatives of TESTO as well as progesterone have been synthesized in order to obtain useful compounds having fewer undesirable masculinizing side effects (body hair growth, loss of scalp hair, acne, seborrhea and loud voice).
Medroxyprogesterone acetate (MPA) is one of the most widely used compounds in the endocrine therapy of advanced breast cancer in women (Mattsson, Breast Cancer Res. Treatm. 3: 231-235, 1983; Blumenschein, Semin. Oncol. 10: 7-10, 1983; Hortobagyi et al., Breast Cancer Res. Treatm. 5: 321-326, 1985; Hailer and Glick, Semin. Oncol. 13: 2-8, 1986; Horwitz, J. Steroid Biochem. 27: 447-457, 1987). The overall clinical response rate of high doses of this synthetic progestin averages 40% in unselected breast cancer patients (Horwitz, J. Steroid Biochem. 27: 447-457, 1987), an efficacy comparable to that of the non-steroidal antiestrogen tamoxifen (Lippman, Semin. Oncol. 10 (Suppl.): 11-19, 1983). Its more general use, however, is for breast cancer relapsing after other endocrine therapeutic modalities. The maximal inhibitory action of medroxyprogesterone acetate (MPA) on human breast cancer cell growth in vitro may be achieved at concentration as low as 1 nM while an approximately 1000-fold higher dose is often required for glucocorticoid action (Poulin et al., Breast Cancer Res. Treatm. 13: 161-172, 1989).
Until recently, the mechanisms underlying the antitumor activity of MPA were poorly understood and have been attributed to interaction with the progesterone receptor. This steroid, however, presents a high affinity for progesterone (PgR) as well as for androgen (AR) and glucocorticoid receptors (GR) in various animal tissues (Perez-Palacios et al., J. Steroid Biochem. 19: 1729-1735, 1983; Janne and Bardin, Pharmacol. Rev. 36: 35S-42S, 1984; Pridjian et al., J. Steroid Biochem. 26: 313-319, 1987; Ojasso et al., J. Steroid Biochem. 27: 255-269, 1987) as well as in human mammary tumors (Young et al., Am. J. Obstet. Gynecol. 137: 284-292, 1980), a property shared with other synthetic progesterone derivatives (Bullock et al., Endocrinology 103: 1768-1782, 1978; Janne and Bardin, Pharmacol. Rev. 36: 35S-42S, 1984; Ojasso et al., J. Steroid Biochem. 27: 255-269, 1987). It is known that in addition to progesterone receptors (PgR), most synthetic progestational agents bind with significant affinity to androgen (AR) as well as glucocorticoid (GR) receptors, and induce biological actions specifically determined by these individual receptor systems (Labrie et al., Fertil. Steril. 28: 1104-1112, 1977; Engel et al., Cancer Res. 38: 3352-3364, 1978; Raynaud et al., In: Mechanisms of Steroid Action (G. P. Lewis, M. Grisburg, eds), MacMiland Press, London, pp. 145-158, 1981; Rochefort and Chalbos, Mol. Cell. Endocrinol. 36: 3-10, 1984; J anne and Bardin, Pharmacol. Rev. 36: 35S-42S, 1984; Poyet and Labrie, Mol. Cell. Endocrinol. 42: 283-288, 1985; Poulin et al., Breast Cancer Res. Treatm. 13: 161-172, 1989). Accordingly, several side effects other than progestational have been noted in patients treated with MPA.
The inhibitory effect of MPA on gonadotropin secretion is clearly exerted through its direct interaction with pituitary AR in the rat (Labrie et al., Fertil. Steril. 28: 1104-1112, 1977; Perez-Palacios et al., J. Steroid Biochem. 19: 1729-1735, 1983) and human (Perez-Palacios et al., J. Steroid Biochem. 15: 125-130, 1981). In addition, MPA exhibits androgenic activity in the mouse kidney (J anne and Bardin, Pharmacol. Rev. 36: 35S-42S, 1980) and in the rat ventral prostate (Labrie, C. et al., J. Steroid Biochem. 28: 79-384, 1987; Labrie C. et al., Mol. Cell. Endocrinol. 68: 169-179, 1990). Despite its high affinity for AR, MPA seldom causes significant virilizing symptoms (ache, hirsutism, etc.) (Hailer and Glick, Semin. Oncol. 13, 2-8, 1986).
The most easily explained adverse side effects of MPA are related to its glucocorticoid-like action with Cushingoid syndrome, euphoria and subjective pain relief (Mattsson, Breast Cancer Res. Treatm. 3: 231-235, 1983; Blossey et al., Cancer 54: 1208-1215, 1984; Hortobagyi et al., Breast Cancer Res. Treatm. 5: 321-326, 1985; Van Veelen et al., Cancer Chemother. Pharmacol. 15: 167-170, 1985). Suppression of adrenal function by MPA is believed to be caused both by an inhibitory action on ACTH secretion at the pituitary level and by direct inhibition of steroidogenesis at the adrenal level (Blossey et al., Cancer 54: 1208-1215, 1984; Van Veelen et al., Cancer Chemother. Pharmacol. 15: 167-170, 1985; Van Veelen et al., Cancer Treat. Rep. 69: 977-983, 1985).
Despite its high affinity for AR, MPA seldom causes significant virilizing symptoms (acne, hirsutism, etc.) (Hailer and Glick, Semin. Oncol. 13: 2-8, 1986). Moreover, its inhibitory effect on gonadotropin secretion is dearly exerted through its direct interaction with pituitary AR in the rat (Labrie et al., Fertil. Steril. 28: 1104-1112, 1977; Perez-Palacios et al., J. Steroid Biochem. 19: 1729-1735, 1983) and human (Perez-Palacios et al., J. Steroid Biochem. 15: 125-130, 1981). In addition, MPA exhibits androgenic activity in the mouse kidney (J anne and Bardin, Pharmacol. Rev. 36: 35S-42S, 1980) and in the rat ventral prostate (Labrie, C. et al., J. Steroid Biochem. 28: 379-384, 1987; Labrie C. et al., Mol. Cell. Endocrinol. 68: 69-179, 1990).
Poulin et al. "Androgen and glucocorticoid receptor-mediated inhibition of cell proliferation by medroxyprogesterone acetate in ZR-75-1 human breast cancer cells", Breast Cancer Res. Treatm. 13: 161-172, 1989) have recently found that the inhibitory effect of medroxyprogesterone acetate (MPA) on the growth of the human ZR-75-1 breast cancer cells is mainly due to the androgenic properties of the compound. The androgenic properties of MPA have been demonstrated in other systems (Labrie C. et al., J. Steroid Biochem. 28: 379-384, 1987; Luthy et al., J. Steroid Biochem. 31: 845-852, 1988; Plante et al., J. Steroid Biochem. 31: 61-64, 1988; Labrie C. et al., Mol. Cell. Endocrinol. 58: 169-179, 1990). Other synthetic progestins have also been shown to possess, in addition to their progesterone-like activity, various degrees of androgenic activity (Labrie et al., Fertil. Steril. 31: 29-34, 1979; Poyet and Labrie, The Prostate 9: 237-246, 1986; Labrie C. et al., J. Steroid Biochem. 28: 379-384, 1987; Luthy et al., J. Steroid Biochem. 31: 845-852, 1988; Plante et al., J. Steroid Biochem. 31: 61-64, 1989).
High dose progestins, especially medroxyprogesterone acetate and megestrol acetate have also been successfully used for the treatment of endometrial cancer (Tatman et al., Eur. J. Cancer Clin. Oncol. 25: 1619-1621, 1989; Podratz et al., Obstet. Gynecol. 66: 106-110, 1985; Ehrlich et al., Am. J. Obstet. Gynecol. 158: 797-807, 1988). The androgen methyltestosterone has been shown to relieve the symptoms of endometriosis (Hamblen, South Med. J. 50: 743, 1987; Preston, Obstet. Gynecol. 2: 152, 1965). Androgenic and masculinizing side effects (sometimes irreversible) are however important with potent androgenic compounds such as testosterone and its derivatives.
High dose MPA as first treatment of breast cancer has shown similar effects as Tamoxifen (Van Veelen et al., Cancer 58: 7-13, 1986). High dose progestins, especially medroxyprogesterone acetate and megestrol acetate have also been successfully used for the treatment of endometrial cancer (Tatman et al., Eur. J. Cancer Clin. Oncol. 25: 1619-1621, 1989; Podratz et al., Obstet. Gynecol. 66: 106-110, 1985; Ehrlich et al., Am. J. Obstet. Gynecol. 158: 797-807, 1988). High dose MPA is being used with a success similar to that of Tamoxifen for the treatment of endometrial carcinoma (Rendina et al., Europ. J. Obstet. Gynecol. Reprod. Biol. 17: 285-291, 1984).
In a randomized clinical trial, high dose MPA administered for 6 months has been shown to induce resolution of the disease in 50% of the patients and a partial resolution in 13% of subjects compared to 12% and 6%, respectively, in patients who received placebo (Telimaa et al., Gynecol. Endocrinol. 1: 13, 1987).
The androgen methyltestosterone has been shown to relieve the symptoms of endometriosis (Hamblen, South Med. J. 50: 743, 1987; Preston, Obstet, Gynecol. 2: 152, 1965). Androgenic and masculinizing side effects (sometimes irreversible) are however important with potent androgenic compounds such as testosterone.
In analogy with the androgen-induced decrease in estrogen receptors in human breast cancer ZR-75-1 cells (Poulin et al., Endocrinology 125: 392-399, 1989), oral administration of MPA to women during the follicular phase caused a decrease in the level of estrogen binding in the endometrium (Tseng and Gurpide, J. Clin. Endocrinol. Metab. 41, 402-404, 1975).
Studies in animals have shown that androgen deficiency leads to osteopenia while testosterone administration increases the overall quantity of bone (Silberberg and Silberberg, 1971; see Finkelstein et al., Ann. Int. Med. 106: 354-361, 1987). Orchiectomy in rats can cause osteoporosis detectable within 2 month (Winks and Felts, Calcif. Tissue Res. 32: 77-82, 1980; Verhas et al., Calif. Tissue Res. 39: 74-77, 1986).
While hirsute oligomenorrheic and amenorrheic women having low circulating E.sub.2 levels would be expected to have reduced bone mass, these women with high androgen (but low estrogen) levels are at reduced risk of developing osteoporosis (Dixon et al., Clinical Endocrinology 30: 271-277, 1989).
Adrenal androgen levels have been found to be reduced in osteoporosis (Nordin et al., J. Clin. Endocr. Metab. 60: 651, 1985). Moreover, elevated androgens in postmenopausal women have been shown to protect against accelerated bone loss (Deutsch et al., Int. J. Gynecol. Obstet. 25: 217-222, 1987; Aloia et al., Arch. Int. Med. 143: 1700-1704, 1983). In agreement with such a role of androgens, urinary levels of androgen metabolites are lower in postmenopausal symptomatic menopausis than in matched controls and a significant decrease in conjugated dehydroepiandrosterone (DHEA) was found in the plasma of osteoporotic patients (Hollo and Feher, Acta Med. Hung. 20: 133, 1964; Urist and Vincent, J. Clin. Orthop. 18: 199, 1961; Hollo et al., Acta Med. Hung. 27: 155, 1970). It has even been suggested that postmenopausal osteoporosis results from both hypoestrogenism and hypoandrogenism (Hollo et al., Lancet:. 1357, 1976).
As a mechanism for the above-suggested role of both estrogens and androgens in osteoporosis, the presence of estrogen (Komm et al., Science 241: 81-84, 1988; Eriksen et al., Science 241: 84-86, 1988) as well as androgen (Colvard et al., Proc. Natl. Acad. Sci. 86: 854-857, 1989) receptors in osteoblasts could explain increased bone resorption observed after estrogen and androgen depletion.
In boys, during normal puberty, an increase in serum testosterone levels procedes an increase in alkaline phosphate activity (marker of osteoblastic activity) which itself precedes increased bone density (Krabbe et al., Arch. Dis. Child. 54: 950-953, 1979; Krabbe et al., Arch. Pediat. Scand. 73: 750-755, 1984; Riis et al., Calif. Tissue Res. 37: 213-217, 1985).
While, in women, there is a rapid bone loss starting at menopause, bone loss in males can be recognized at about 65 years of age (Riggs et al., J. Clin. Invest. 67: 328-335, 1987). A significant bone loss is seen in men at about 80 years of age, with the accompanying occurrence of hip, spine and wrist fractures. Several studies indicate that osteoporosis is a clinical manifestation of androgen deficiency in men (Baran et al., Calcif. Tissue Res. 26: 103-106, 1978; Odell and Swerdloff, West. J. Med. 124: 446-475, 1976; Smith and Walker, Calif. Tissue Res. 22 (Suppl.): 225-228, 1976).
Although less frequent than in women osteoporosis can cause significant morbidity in men (Seeman et al., Am. J. Med. 75: 977-983, 1983). In fact, androgen deficiency is a major risk for spinal compression in men (Seeman et al., Am. J. Med. 75: 977-983, 1983). Decreased radial and spinal bone density accompanies hypogonadism associated with hyperprolactinemia (Greespan et al., Ann. Int. Med. 104: 777-782, 1986) or anaorexia nervosa (Rigotti et al., JAMA 256: 385-288, 1986). However, in these cases, the role of hyperprolactinemia and loss in body weight is uncertain.
Hypogonadism in the male is a well-recognized cause of osteoporotic fracture (Albright and Reinfenstein, 1948; Saville, Clin. End. Metab. 2: 177-185, 1973). Bone density is in fact reduced in both primary and secondary hypogonadism (Velentzas and Karras. Nouv. Presse M edicale 10: 2520, 1981).
Severe osteopenia as revealed by decreased cortical and trabecular bone density was reported in 23 hypogonadotropic hypogonadal men (Finkelstein et al., Ann. Int. Med. 106: 354-361, 1987; Foresta et al., Horm. Metab. Res. 15: 56-57, 1983). Osteopenia has also been reported in men with Klinefelter's syndrome (Foresta et al., Horm. Metab. Res. 15: 206-207, 1983; Foresta et al., Horm. Metab. Res. 15: 56-57, 1983; Smith and Walker, Calif. Tissue Res. 22: 225-228, 1977).
Androgenic-reversible decreased sensitivity to calcitonin has been described in rats after castration (Ogata et al., Endocrinology 87: 421, 1970; Hollo et al., Lancet 1: 1205, 1971; Hollo et al., Lancet 1: 1357, 1976). In addition, serum calcitonin has been found to be reduced in hypogonadal men (Foresta et al., Horm. Metab. Res. 15: 206-207, 1983) and testosterone therapy in castrated rats increases the hypocalcemic effect of calcitonin (McDermatt and Kidd, End. Rev. 8: 377-390, 1987).
Albright and Ruferstein (1948) originally suggested that androgens increase the synthesis of bone matrix. Androgens have also been shown to increase osteoid synthesis and mineralization in chicken (Puche and Rosmano, Calif. Tissue Res. 4: 39-47, 1969). Androgen therapy in hypogonadal men increases skeletal growth and maturation (Webster and Hogkins, Proc. Soc. Exp. Biol. Med. 45: 72-75, 1940). In addition, testosterone therapy in man has been shown to cause positive nitrogen, calcium and phosphate balance (Albright, F., Reinfenstein, E.C. In: The parathyroid glands and metabolic bone disease. Williams and Williams Co.: Baltimore, pp. 145-204, 1948). As studied by bone histomorphometry, testosterone therapy in hypogonadal males resulted in increases in relative osteoid volume, total osteoid surface, linear extend of bone formation and bone mineralization (Barau et al., Calcif. Tissue Res. 26: 103-106, 1978).
Treatment with testosterone has been shown to increase osteoid surfaces and beam width with unchanged or reduced oppositional rates, thus indicating and increase in total bone mineralization rate (Peacock et al., Bone 7: 261-268, 1986). There was also a decrease in plasma phosphate probably due to an effect on renal tubular reabsorption of phosphates (Selby et al., Clin. Sci. 69: 265-271, 1985).
Cortical bone density increases in hyperprolactinemic men with hypogonadism when testicular function is normalized (Greenspan et al., Ann. Int. Med. 104: 777-782, 1986; Greenspan et al., Ann. Int. Med. 110: 526-531, 1989). Testosterone therapy increases bone formation in men with primary hypogonadism (Baron et al., Calcif. Tissue Res. 26: 103-106, 1978; Francis et al., Bone 7: 261-268, 1986).
In 21 hypogonadal men with isolated GnRH deficiency, normalization of serum testosterone for more than 12 months increased bone density (Kinkelstein et al., J. Clin. Endocr. Metab. 69: 776-783, 1989). In men with already fused epiphyses, however, there was a significant increase in cortical bone density while no significant change was observed on trabecular bone density, thus supporting previous suggestions of variable sensitivity of cortical and trabecular bone to steroid therapy.
Previous studies with anabolic steroids in small numbers of patients have suggested positive effects on bone (Lafferty et al., Ann. J. Med. 36: 514-528, 1964; Riggs et al., J. Clin. Invest. 51: 2659-2663, 1972; Harrison et al., Metabolism 20: 1107-1118, 1971). More recently, using total body calcium measurements by neutron activation as parameter, the anabolic steroid methandrostenolone has shown positive and relatively long-term (24-26 months) effects in a double-blind study in postmenopausal osteoporosis (Chessnut et al., Metabolism 26: 267-277, 1977; Aloia et al., Metabolism 30: 1076-1079, 1981).
The anabolic steroid nandrolone decanoate reduced bone resorption in osteoporotic women (Dequeker and Geusens, Acta Endocrinol. 271 (Suppl.): 45-52, 1985) in agreement with the results observed during estrogen therapy (Dequeker and Ferin, 1976, see Dequeker and Geusens). Such data confirm experimental data in rabbits and dogs when nandrolone decanoate reduced bone resorption (Ohem et al., Curr. Med. Res. Opin. 6: 606-613, 1980). Moreover, in osteoporotic women (Dequeker and Geusens, Acta Endocrinol. (Suppl.) 271: 45-52, 1985) the anabolic steroid not only reduced bone loss but also increased bone mass. Vitamin D treatment, on the other hand, only reduced bone resorption.
Therapy of postmenopausal women with nandrolone increased cortical bone mineral content (Clin. Orthop. 225: 273-277). Androgenic side effects, however, were recorded in 50% of patients. Such data are of interest since while most therapies are limited to an arrest of bone loss, an increased in bone mass was found with the use of the anabolic steroid nandrolone. A similar stimulation of bone formation by androgens has been suggested in a hypogonadal male (Baran et al., Calcif. Tissue Res. 26: 103, 1978). The problem with regimens which inhibit bone resorption with calcium, calcitriol or hormones is that they almost certainly lead to suppression of bone formation (Need et al., Mineral. Electrolyte Metabolism 11: 35, 1985). Although, Albright and Reiferestein (1948) (See Need, Clin. Orthop. 225: 273, 1987) suggested that osteoporosis is related to decreased bone formation and will respond to testosterone therapy, the virilizing effects of androgens have made them unsuitable for the treatment of postmenopausal women. Anabolic steroids, compounds having fewer virilizing effects, were subsequently developed. Although, minimal effects have been reported by some (Wilson and Griffin, Metabolism 28: 1278, 1980) more positive results have been reported (Chessnut et al., Metabolism 32: 571-580, 1983; Chessnut et al., Metabolism 26: 267, 1988; Dequeker and Geusens, Acta Endocrinol. (Suppl. 110) 271: 452, 1985). A randomized study in postmenopausal women has been shown an increase in total bone mass during treatment with the anabolic steroid stanazolol although side effects were recorded in the majority of patients (Chessnut et al., Metabolism 32: 571-580, 1983).
As mentioned above, the doses of "progestins" (for example medroxyprogesterone acetate) used for the standard therapy of breast cancer are accompanied by undesirable important side effects (especially those related to interaction of the steroid with the glucocorticoid receptor, especially Cushingoid syndrome, euphoria) (Mattsson, Breast Cancer Res. Treatm. 3: 231-235, 1983; Blossey et al., Cancer 54: 1208-1215, 1984; Hortobagyi et al., Breast Cancer Res. Treatm. 5: 321-326, 1985; Von Veelen et al., Cancer Chemother. Pharmacol. 15: 167-170, 1985).
The term "progestin" refers to derivatives of progesterone and testosterone. Such progestins have, at times, been synthesized with the aim of developing compounds acting as analogs of progesterone on the progesterone receptors, especially for the control of fertility. With the availability of new and more precise tests, however, it became evident that such compounds, originally made to interact exclusively with the progesterone receptor, do also interact, frequently with high affinity, with the androgen receptor (Labrie et al., Fertil. Steril. 28: 1104-1112, 1977; Labrie et al., Fertil. Steril. 31: 29-34, 1979; Labrie, C. et al., J. Steroid Biochem. 28: 379-384, 1987; Labrie C. et al., Mol. Cell. Endocrinol. 68: 169-179, 1990). Sometimes, the androgenic activity of these compounds, especially at low concentrations, becomes more important than the true progestin activity. This is the case, for example, for medroxyprogesterone acetate (Poulin et al., Breast Cancer Res. Treatm. 13: 161-172, 1989).
A problem with prior-art treatments of breast and endometrial cancer with synthetic progestins is the side effects observed with such treatments. The blockade of estrogens, another common treatment for breast cancer, would have undesirable deleterious effects on bone mass in women. Similarly, blockade of estrogens, a common treatment for endometriosis, has similar undesirable deleterious effects on bone mass in women.
Contraceptive preparations which allow protection for extended periods of time have been developped over the last 25 years. This include steroids with intrinsic long action after injection (e.g. Depoprovera; or more recently, through the use of extrinsic delivery systems, e.g. implants, microspheres, vaginal rings, I.U.Ds., etc.). Today, MPA and norethisterone (NET)-enanthate are used in family planning programs. In 1985, it was estimated that 4 million women were taking MPA and almost one million NET-enanthate (Hall, P. E., Long-acting injectable preparations. Fertility Regulation, Today and Tomorrow (Diczfalusy, E., Bydeman, M., eds), Raven Press: New York, pp. 119-141, 1987). In addition, it is estimated that 0.5 million women in Latin America and 1.0 million women in China are taking various once-a-month injectable preparations containing one progestogen and an estrogen (Hall, 1987, same ref. as above). Contraceptive preparations which allow protection over extended periods of time have been developped over the last 25 years.
An overview of two long-acting contraceptive steroids is presented in Contraception, May 1977, vol. 15, no. 5, pp. 513-533.
Depoprovera (25 mg) in combination with 5 mg estradiol cypionate has been given once-a-month (injection) for fertility control (WHO, Said et al., Contraception, 37: 1-20, 1988) Little difference in efficacy and side effects was seen when comparing ti the once-a-month injection of 50 mg norethisterone enanthate and 5 mg estradiol valerate. More than 10,000 women-month were studied in each group. The combination MPA-E.sub.2 cypionate was highly effective as contraceptive since no pregnancy was using a once-a-month injection was relatively high at 35% at one year (WHO, Said et al., Contraception 37: 11-20, 1988) while bleeding irregularities were involved in only about 6.1% and amenorrhea in 2.1% of women. Late for injection, personal reasons and lost to follow-up amounted to 18% of discontinuations. Such data indicate the need for more easily acceptable schedules of adminstration.
DepoMPA (also called Depoprovera) used alone (150 mg, I.M. every 3 months) in 20,498 women-month has shown a pregnancy rate of 0.1.+-.0.1% and 15.0.+-.1.0% bleeding irregularities with an 11.9.+-.1.0% incidence of amenorrhea (WHO, Said et al., Contraception 37: 1-20, 1988). In a smaller study (5434 women-month), DepoMPA, at the same dose, led to a discontinuation rate of 40.7.+-.2.0% while bleeding irregularities and amenorrhea occurred in 14.7.+-.1.5% of patients.
Previous use of MPA has been through oral administration or intramuscular injection (Depoprovera). Oral administration is limited by problems of compliance and fluctuating blood levels while release of MPA from Depoprovera injection is rapid at first and declines in a highly variable fashion at later time intervals. There is thus the need for a controlled release formulation of MPA which delivers constant amounts of the steroid for defined long time periods assuring patient's compliance and increasing efficacy through the delivery of constant blood levels of the drug to the tissue(s) in need of treatment. Similar arguments apply to MGA.
Microencapsulation drug delivery systems have been widely developed during the last thirty years for controlled release of therapeutic agents, especially by incorporation of the active agents into biodegradable polyesters such as poly(.epsilon.-caprolactone), poly(.epsilon.-caprolactone-CO-DL-lactic add), poly(DL-lactic add), poly(DL-lactic add-CO-glycolic add) and poly(.epsilon.-caprolactone-CO-glycolic acid). See, for example and references, R. W. Baker (R. W. Baker, Controlled release of biologically active agents, John Wiley and Sons Ed. , N.Y., 1987. ), F. Lim (F. Lim, Biomedical Application of Microencapsulation, Franklin Lim, Ed. CRC Press, BocaRaton, 1984)
In U.S. Pat. No. 3,773,919 G. A. Boswell and R. M. Scribner disclose the use a polylactide-drug mixtures, especially steroids such as medroxyprogesterone acetate, for slow sustained release of the drugs.
In DE 3 503 679, Carli discloses medroxyprogesterone acetate formulations by combining with water swellable water insoluble polymer.
In Wo 8 807 816, R. J. Leonard discloses fused recrystallised steroid drug pellet useful as sustained release implant.
In U.S. Pat. No. 4,818,542, DeLuca et al. disclose the use and making of porous microspheres for drug delivery.
In DE 2 010 115, Farbenfabriken Bayer AG disclose the preparation of solid sprayable microgranulates for retarded release of pharmaceuticals.
In U.S. Pat. No. 4,166,800, F. W. Fong disclose the production of microspheres by adding phase separation agent at low temperature.
In U.S. Pat. No. 4,897,268, Tice et al. disclose drug delivery system including poly[DL-lactide-co-glycolide)] for encapsulation.
In U.S. Pat. No. 4,107,071, R. G. Bayless disclose the preparation of microcapsules of partially hydrolyzed copolymer of ethylene and vinyl acetate.
In DE 2 051 580, Du Pont and Co disclose the preparation of controlled release parenteral pellets.
In U.S. Pat. No. 4,622,244, Lapka et al. disclose the encapsulation of particulate or material with phase separation, and isolation of microcapsules at low temperature.
In U.S. Pat. No. 4,987,268, E. S. Nuwayser and W. A. Nucefora disclose the preparation a composite core microparticles.
Wise et al (D. L. Wise Lactic/Glycolic Acid Polymers, Biology & Medicine, G. Gregotiadis ed., New York Academic Press, pp. 237-270, 1979.) describe the application of Lactic / Glycolic Acid (co)Polymers in medicine. See also Lewis, "Controlled Release of Bioactive Agents from Lactide/Glycolide Polymers", Drug and Pharmaceutical Sciences, vol. 45, pp. 1-41, 1990.
An injectable sustained release preparation containing norethisterone as the contraceptive steroid has shown uniform release for 2 months in the rat (Anderson et al., Contraception 13: 375-384, 1976). The cryogenically ground particles 90-180 .mu.m in size contained 20% of norethisterone incorporated in a biodegradable polymer matrix synthesized from L(+)lactic acid to a molecular weight of 200,000. A preparation (powder of 90-180 .mu.m particle size) containing 20% norethisterone in a polymer synthesized from 90 parts of L-lactide by weight and 10 parts of glycolide to a molecular weight of 200,000 released the compound for approximately 2 months in baboons (Gresser et al., Contraception 17: 253-266, 1978). However, the zero rate of release found in rats was not confirmed in this study performed in primate (Beck and Tice, In Long acting steroid contraception (D. R. Mishell, ed) Raven Press: New York, pp. 175-199, 1983). The injectable DL-PLA NET microcapsule system is the only form that has been studied in detail under in vivo conditions (Review by Beck and Tice. In Long acting steroid contraception (D. R. Mishell, ed) Raven Press: New York, pp. 175-199, 1983).
Most of the techniques used for the preparation of microparticles need the use of organic solvents which remain present at a non negligible percentage and may cause local or systemic unwanted toxic effects. Other prior art techniques need the use of high temperature with potential unwanted thermal decomposition of the steroid and/or polymer.
A problem with prior-art treatments of breast and endometrial cancer with MPA and megestrol acetate is the side effects observed with such treatments. A problem with the use of derivatives of 19-nortestosterone such as norgestrel, norethisterone and norethindrone is that such compounds possess estrogenic activity (Vilchis et al., J. Ster. Biochem. 24: 525-531, 1986; Larrea et al. J. Ster. Biochem. 27: 657-663, 1987; Poulin et al., Breast Cancer Res. Treatm. 17: 197-210, 1990). Such estrogenic activity could well have a negative effect on breast cancer incidence over long-term use.
There is thus a need in the art of the treatment and prevention of estrogen-dependent diseases (as well as osteoporosis and contraception) of injectable long-acting delivery systems of medroxyprogesterone acetate and megestrol acetate which could maintain the circulating concentration of these steroids at a low level for long periods of time (e.g. 1 month and longer) and which contain negligible amounts of toxic residual organic solvent and/or thermal degradation impurities caused by exposing the therapeutical formulation to excessive heat.
Especially for contraceptive and preventive purposes, long-term delivery systems of MPA, MGA, or other androgenic compounds with negligible masculinizing activity should have a positive impact on costs of the health care system.